A. Field of the Invention
The invention relates generally to wound treatment systems and methods, and more specifically to a system and method of treating a wound by combining ultrasonic debridement and reduced pressure therapy.
B. Description of Related Art
Wounds to the skin typically fall into two categories: chronic and acute. The natural healing mechanism in animals repairs acute wounds quickly by closing the wound, filling in lost tissue, and covering the wound with a new layer of skin. Those having observed wound healing in children often observe the healing of small acute wounds in a few days. Chronic wounds are often wounds in which the natural healing mechanisms have been impaired. Chronic wounds typically linger for extended periods of time and may never heal. Such wounds are often observed among the elderly or people suffering from diabetes. Another problem associated with wounds is infection. Infection is the invasion of a wound by pathogenic microorganisms or bacteria that grow within the wound, produce toxins, and subsequently injure the tissue surrounding the wound. To reduce the chance for infection of a wound, the wound is first cleaned to remove those microorganisms or bacteria that may have invaded the wound when it was created. Next, the wound typically is debrided or sterilized to remove nonviable or necrotic tissue and any microorganisms or bacteria resident within the wound. The third step in the treatment of a wound is to apply a dressing to cover the wound and promote its healing with the application of medication.
The debriding of a wound is often accomplished with mechanical surgical methods, referred to as sharps debridement. Specifically, the non-viable or necrotic tissue is cut from the wound and removed. Sometimes, surgical treatment of a wound will trigger the body's response to an acute wound and the wound will heal.
While the debridement process often involves cutting away tissue within the wound, recent efforts have involved the use of ultrasonic energy. A description of the use of ultrasonic energy and its use on skin appears in the following U.S. patents: Suroff, U.S. Pat. No. 4,040,414 (Ultrasonic Personal Care Instrument and Method); Beaty, et al., U.S. Pat. No. 5,312,329 (Piezo Ultrasonic and Electrosurgical Handpiece); Sakurai, et al., U.S. Pat. No. 5,391,144 (Ultrasonic Treatment Apparatus); Novak, et al., U.S. Pat. No. 6,171,265 (Handpiece for Use With a Multifunctional Operating Endoscopic Instrument); and in the following published PCT application: Babaev, WO 97/17933 (Method of Spraying A Surface Using Ultrasonic Radiation). Further descriptions are found in the following articles: King, et al., Burns, Vol. 22, No. 4, Pg. 307, (Debridement of Burn Wounds with a Surgical Ultrasonic Aspirator); Vanderburgh, et al., Gynecologic Oncology, Vol. 39, Pg. 103 (1990); (Debridement of Vaginal Radiation Ulcers Using the Surgical Ultrasonic Aspirator); and Herte, et al., Am. Society of Plastic and Reproductive Surgeons Prelim. Rpt. (November 1978); (Comparative Wound Healing in Animal Subjects Using the Cavitron Ultrasonic Surgical Aspirator vs. Conventional Surgical Instrument).
Further, in recently issued U.S. Pat. No. 6,916,296 to Soring, et al., entitled System for Antiseptic Surgery, a system using ultrasound was proposed for wound healing. Specifically, a device called a sonotrode is placed in a liquid within the wound. The sonotrode generates ultrasonic vibrations and cavitations in the liquid that leads to destruction of the bacteria cells. Specifically, the high level of energy released in the fluid kills the bacteria cells by rupturing their cell walls. While U.S. Pat. No. 6,916,296 reports a significant reduction in germ count in a wound, it is also taught that high levels of energy can be used for very short periods of time, or that lower levels of energy can be used for longer periods of time—up to several minutes.
In practice, the use of ultrasound to debride wounds involves relatively high amounts of ultrasonic energy typically applied in a focused manner to energize a relatively small area of a wound for a short period of time. The area over which ultrasonic energy is broadcast at any given time is typically less than about 5 cm2. Since the treatment is focused, the ultrasonic energy is typically only applied for less than about 60 seconds to any specific area.
Following debridement, wounds are dressed to cover the wound and promote healing. In recent years, it has been found that the application of reduced pressure to a wound promotes healing in many cases. This is particularly evident in chronic wounds, such as those that develop in elderly patients, but may also occur in any type of wound. Studies have also revealed that frequent irrigation of a wound helps promote healing by aiding in the removal of wound exudate, unwanted bioburden, and optionally, serving as an effective vehicle for the application & delivery of medication. Examples of wound treatment systems employing some of these techniques are found in the following U.S. patents: Zamierowski, U.S. Pat. No. 4,969,880 (Wound Dressing and Treatment Method); Zamierowski, U.S. Pat. No. 5,100,396 (Fluidic Connection System and Method); Zamierowski, U.S. Pat. No. 5,261,893 (Fastening System and Method); Zamierowski, U.S. Pat. No. 5,527,293 (Fastening System and Method); Argenta, et al., U.S. Pat. No. 5,636,643 (Wound Treatment Employing Reduced Pressure); Argenta, et al., U.S. Pat. No. 5,645,081 (Method of treating tissue damage and apparatus for same); Zamierowski, U.S. Pat. No. 6,071,267 (Medical Patient Fluid Management Interface System and Method); Vogel, et al., U.S. Pat. No. 6,135,116 (Method for Treating Ulcers); and Hunt, et al., U.S. Pat. No. 6,142,982 (Portable wound treatment apparatus).
While ultrasonic debridement has been taught as a way of initially clearing a wound of nonviable or necrotic tissue, the procedure has not gained acceptance as part of broad-based system for accelerating healing of a wound, in part due to the labor-intensive process involved with traditional ultrasonic debridement. A need currently exists for a system that utilizes ultrasonic energy at low energy levels over a prolonged period of time to debride a wound. For ease of use and improvement in performance, the application area over which the ultrasonic energy is applied should be relative large compared to existing procedures, which call for a more focused beam. Also needed is a system that employs a non-focused, low energy debridement procedure such as ultrasound, with reduced pressure therapy, and optionally, with a system providing fluid irrigation and removal of debrided tissue.
All of the patents, patent applications, and other publications referenced herein are incorporated by reference to the maximum extent allowable by law.